In the related art, as a fixing structure of an indoor lamp that attaches a lamp unit, such as a room lamp, to an interior wall member, such as a roof trim, there is known a indoor lighting device (lamp unit) for vehicle (for example, refer to PTL 1) that is fixed in a state where a design part provided on the indoor side through an attachment hole of the ceiling plate (interior wall member) is assembled to a functional part provided on the outdoor side to hold a ceiling plate.
In the fixing structure of such an indoor lighting device for vehicle, when the design part and the functional part are assembled to each other, a locked portion of an elastically deformable manipulation plate provided on the functional part is locked to a locking claw that is provided at a lateral plate of the design part and protrudes laterally. Further, the release of the locked portion from the locking claw is prevented by a spacer that abuts a face opposite to the face of the manipulation plate that faces the lateral plate.
Thus, for example, even in a case where a strong impact is applied to the lamp unit when a curtain air bag or the like is operated, it is possible to prevent unexpected deflection of the manipulation plate, and it is possible to prevent the decoupled design part from falling off and scattering in the vehicle interior.